Question

Sea la parábola y= 1/2 x² + bx + 2. Se sabe que xv = 4. Calcúlense b e yv.

Answer 1

$y= \frac{1}{2} x^2+bx+2 \\ \\ x_{v} =4 \\ \frac{-b}{2a} =4 \\ \frac{-b}{2* \frac{1}{2} } =4 \\ \\ -b=4 \\ b=-4 \\ \\ y_{v} = \frac{1}{2} x_{v} ^2+b x_{v} +2 = \frac{1}{2} 4 ^2+(-4)*4 +2 =8-16+2=-6 \\ y_{v} =-6$